Kew York Agricultural Experiment Station. 169 



mation of cheese flavors. These may or may not arise from 

 common causes. The casein begins to nndergo change at once, 

 while the formation of flavors begins some time later, after 

 which the two progress simultaneously. These two groups of 

 phenomena cannot be measured by the same means or standards. 



Duclaux, Adametz, Weigmann and their disciples have 

 directed their attention to the formation of flaA'ors and have 

 quite generally relied upon the odor and physical appearance of 

 their material in judging of the rate and character of the 

 ripening. In those cases in which they have gone more fully 

 into the solubility of the casein, they have usually determined this 

 point by its ability to pass through a porcelain filter, a method 

 wliich von Freudenrich & Jensen'^ have shown to be extremely 

 liable to error in practice. They have rarely attempted to show 

 that the species of bacteria which they look upon as the causal 

 ones are present in cheese in any considerable quantities. They 

 have, for the most part, confined themselves to showing that 

 pure cultures of these species are able, by means of excreted 

 enzymes, to digest the casein of milk and at the same time to 

 form cheese-like odors. In some cases they have made cheese 

 with the addition of pure cultures or of solutions of their enzymes 

 and have stated that the resulting product was better flavored 

 than cheese made in the usual way. In establishing this point, 

 however, they were handicapped by the lack of accurate 

 standards for measuring such relations. 



Recently Adametz and Winkler^ have placed a culture of one 

 of these bacilli upon the market under the trade name of 

 " Tyrogene," its use being expected to result in the production 

 of a desirable Emmenthaler flavor in cheese. Some preliminary 

 tests by von Freudenrich^ have failed to indicate that it will 

 accomplish this desired end. 



When the study of the kinds of bacteria present in cheese 

 was extended so as to include the numbers of each kind, it was 

 found that the enzyme-forming bacteria previously mentioned 



»v. Freiidenreieh and Jensen. Lanrlvr. Jabrb. d. Scbweiz., 14:109 (1899). 

 * Winkler. Molkerei Ztg.. 14:817 (1900). 

 •v. Freudenreich. Ann. Agr. Suisse (1901), 



